Replies to LegCo questions
LCQ5: Prevention of Japanese encephalitis
Following is a question by the Hon Leung Che-cheung and a reply by the Secretary
for Food and Health, Professor Sophia Chan, in the Legislative Council today
(November 1):
Question:
Japanese encephalitis (JE) is a mosquito-borne disease. Most people infected
with JE virus have symptoms that are comparatively mild or not apparent. Since
January this year, there have been five JE cases in Hong Kong, all of which
being locally acquired cases. The patients in two of the aforesaid cases live in
Tin Shui Wai and in another case, which is the world's first case of JE being
transmitted by blood transfusion, the blood donor concerned also lives in Tin
Shui Wai. Some members of the public suspect that quite a number of Tin Shui Wai
residents have been infected with JE virus. Besides, it has been reported that
there is a serious mosquito problem in Tin Shui Wai and the reasons for that
include the failure of the Food and Environmental Hygiene Department officers to
gain access to private farmlands in the district to carry out anti-mosquito
work. In this connection, will the Government inform this Council:
(1) apart from deploying additional manpower to carry out anti-mosquito work in
Tin Shui Wai, whether the authorities have, since January this year, targeted
the pig farms near the district in carrying out anti-mosquito work; if so, of
the details;
(2) given that the findings of a survey conducted by me earlier have revealed
that the level of awareness of JE vaccines among Tin Shui Wai residents was
rather low, and a number of JE cases have occurred in the district, of the
reasons why the authorities have not considered providing vaccination for
residents in the district and stepping up publicity in this respect; and
(3) whether the Government monitored in the past three years the anti-mosquito
work carried out at private places (particularly on private lands in Tin Shui
Wai); if so, of the details?
Reply:
President,
The Hong Kong Special Administrative Region Government has all along attached
importance to pest, rodent and mosquito control. The Food and Environmental
Hygiene Department (FEHD) set up four Pest Control Inspection Teams in May this
year to step up inspections of construction sites and potential sites for
mosquito breeding and enforcement actions against mosquito breeding. Among the
five local Japanese encephalitis (JE) cases this year, two patients live in Tin
Shui Wai and the blood donor involved in a case of JE being transmitted by blood
transfusion also lives in Tin Shui Wai. Against this background, the Government
has strengthened anti-mosquito work in Tin Shui Wai. Where the circumstances so
warranted, the Government may consider exercising its authority under section 27
of the Public Health and Municipal Services Ordinance (Cap 132) to enter private
premises (including private land) for carrying out anti-mosquito work.
My reply to various parts of the question raised by Hon Leung is as follows:
(1) In view of the above JE cases, the FEHD has carried out targeted
anti-mosquito work, including conducting entomological surveys and carrying out
anti-mosquito work in areas within a two-kilometre radius of the residence of
the patients and the places visited by them during the incubation period.
District task force meetings have also been conducted to liaise with relevant
Government departments and organisations to step up anti-mosquito work in areas
within their purview. In response to the above local JE cases, the FEHD has
collected and tested 53 mosquito samples. All samples were found negative for JE
virus.
The relevant Government departments have also stepped up their anti-mosquito
work accordingly. Apart from strengthening the anti-mosquito work in Tin Shui
Estate and other relevant housing estates in Tin Shui Wai, the Housing
Department has installed six additional mosquito trapping devices in Tin Shui
Estate with a view to reducing the number of adult mosquitoes at public areas
and lowering the risk of contact between mosquitoes and humans.
In August and September this year, the FEHD increased the number of pest control
roving teams in Yuen Long district by two teams to 22 teams under the current
contract under the Home Affairs Department's District-led Actions Scheme, so as
to step up the anti-mosquito work at the public areas in the vicinity of Tin
Shui Wai Open Nullah, Tin Heng Estate, Tin Chak Estate, Tin Yan Estate, Tin Wah
Estate and Tin Shui Estate.
The FEHD has also conducted joint site visits with the Agriculture, Fisheries
and Conservation Department (AFCD) to the Wetland Park and the pig farms
situated within the two-kilometre radius of Tin Shui Estate to offer technical
advice on mosquito prevention and elimination. Other actions taken are as
follows:
(i) Notices have been issued by the AFCD to advise pig farmers to take
anti-mosquito measures, such as installing mosquito trapping devices in their
pig farms to lower the risk of contact between mosquitoes and pigs;
(ii) Health talks on anti-mosquito work have been organised for the pig farmers;
and
(iii) Concerted efforts have been made by relevant bureaux and departments to
step up anti-mosquito work in the vicinity of pig farms.
After conducting inspections on the pig farms, the two departments considered
the measures implemented by the pig farmers to be effective.
On top of the above, the FEHD has also strengthened the surveillance of JE
vectors since October 2015. In the period between January and August this year,
a total of 251 mosquito samples were collected and tested, all of which were
found negative for the JE virus.
(2) In general, when determining whether to provide vaccination to a specific
population, the Government must take into account well-established scientific
criteria and a number of public health considerations, including the efficacy
and side effects of the vaccine, the availability of other effective preventive
measures, cost-effectiveness, the administrative arrangements for vaccination
and adequacy of vaccine supply.
The Scientific Committee on Vector-borne Diseases (the Committee) under the
Centre for Health Protection of the Department of Health has discussed the use
of JE vaccination in Hong Kong as a measure to prevent JE at several meetings.
The Committee considered the territory-wide incidence rate of local JE cases in
Hong Kong to be low. Even in high-risk areas such as those near pig farms, the
incidence rate was comparable to the incidence rates in countries and areas
where JE vaccination has been used to prevent JE after incorporation of the JE
vaccine into the immunisation programmes in those countries and areas. The
Committee considered that although serious side effects are uncommon with modern
JE vaccines, the number of such serious side effects is directly proportional to
the number of people vaccinated. The Committee estimated that the number of
serious side effects due to the JE vaccine far outweighs the protective benefits
of the vaccine in preventing JE in areas where JE occurs infrequently such as
Tin Shui Wai. The Committee has thus concluded that the risks of using JE
vaccine in the Hong Kong population, including the population living within a
two-kilometer radius of pig farms, to prevent JE outweigh its benefits. The
Committee also recommended other measures, such as mosquito control and personal
protection against mosquito bites, to prevent JE.
(3) To effectively prevent and control the breeding of mosquitoes, the
Government's efforts alone are not enough. We need the participation of various
sectors and the community. The most effective way is for the public to start at
individual level and at home by removing stagnant water in their premises and
taking personal protective measures against mosquitoes. If the owners of private
properties have difficulties in conducting the mosquito prevention work, the
FEHD will be ready to offer appropriate assistance. The FEHD may also consider
exercising the authority to enter private premises, including private land, to
carry out anti-mosquito work if necessary. For example, the FEHD has been
installing mosquito screens at vent pipes of septic tanks in private village
houses, including private village houses in more than 150 villages in Yuen Long
District, since March 2016 to prevent the breeding of mosquitoes in the tanks.
Ends/Wednesday, November 1, 2017
Issued at HKT 16:12
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